Features of the mql5 language, subtleties and tricks - page 65

[Konstantin]

how to reduce the size of the file with binary data to the new data size, without removing the file itself, or only through calling external dll can be implemented?

[TheXpert]

Konstantin:

How to reduce file with binary data to the new data size, without removing the file itself, or only by calling external dll can be implemented?

I need an analogue of SetEndOfFile function.

It was asked about it about 6 years ago

[Konstantin]

Combinator:

We need an analogue of the SetEndOfFile function.

It was asked about it about 6 years ago

That's what I'm writing about )) because it's not kasher to do it via external dll or file deletion

[fxsaber]

Combinator:

We need an analogue of the SetEndOfFile function.

It was asked about it about 6 years ago.

bool SetEndOfFile( const string FileName, const uint Size, const int Commong_Flag = 0 )
{
  uchar Buffer[];
  
  return((FileLoad(FileName, Buffer, Commong_Flag) > Size) && ArrayResize(Buffer, Size) && FileSave(FileName, Buffer, Commong_Flag)));
}

[Konstantin]

fxsaber:

the file will change its size only upwards, if the data array is reduced, the file will remain the same size

[fxsaber]

Konstantin:

file will change its size only upwards, if the data array is reduced, the file will remain with the same size

Decreases.

[TheXpert]

fxsaber:

That's a hell of an overhead.

[fxsaber]

Combinator:
That's a hell of an overkill.

Absolutely!

[fxsaber]

Once again about double

Forum on trading, automated trading systems and trading strategies testing

Bugs, bugs, questions

fxsaber, 2018.01.15 11:53

Because the input fmod is double. Double can't store a huge number of integers. For example, your case:

Print(DoubleToString((double)131472503841474907, 0)); // 131472503841474912

Do this.

long fmod( const long Value, const long Value2 )
{
  return(Value % Value2);
}

Using the float example, you can quickly understand the peculiarity of double

#define  PRINT(A) Print(#A + " = " + (string)(A))

void OnStart()
{
  for (int i = 0; i < INT_MAX; i++)
    if ((int)(float)i != i)
    {
      PRINT(i);
      PRINT((float)i);
      PRINT((double)i);
      
      break;
    }
}

Result

i = 16777217
(float)i = 16777216.0
(double)i = 16777217.0

SZY double doesn't lose the information of the whole int-range, not so with long.

[TheXpert]

Konstantin:

This is what I'm writing about )) because it's not kasher to do through external dll or delete a file

saw it, wanted to but forgot